The present invention relates to a motor vehicle with a riding saddle, such as a two-wheeled or three-wheeled motorcycle for example, the motor cycle having a frame including a main pipe which is employed as an air intake passage.
One motor vehicle with a riding saddle such as a two-wheeled or three-wheeled motorcycle has a frame including a head pipe, a main pipe, and a down pipe, the main and down pipes extending rearwardly from the head pipe. The head pipe, the main pipe, and the down pipe are interconnected at a front end of the frame, with a gusset welded to the front frame end and surrounding a space. An air intake port is defined in the front portion of the main pipe and opens in the space surrounded by the gusset. The gusset has an air inlet defined in a side thereof surrounded by an air guide member opening in the forward direction. The main pipe has a rear portion connected to an air cleaner in communication therewith. External air is introduced through the air guide member, the air inlet, and the air intake port into the main pipe, and supplied through the main pipe to the air cleaner. The air supplied to the air cleaner is then fed therefrom through a connecting tube to a carburetor. Such an air intake structure is disclosed in a U.S. patent application filed on Feb. 5, 1985 and assigned to the same assignee as that of the present patent application.
The aforesaid said intake structure allows external air to be supplied smoothly to the air cleaner, with the main pipe being used as a member for introducing external air.
Where a water-cooled engine is mounted on the motor vehicle of the type described above, it is necessary to install a radiator in an optimum position which meets various conditions. In the foregoing U.S. patent application, the radiator is disposed directly below a fuel tank placed on the main pipe, making the fuel tank small in fuel storage capacity and imposing limitations on the design freedom to change the position of the radiator.